最近在項目中應用到springboot與mybatis，在進行整合過程中遇到一些坑，在此將其整理出來，便于以后查閱與復習。
項目運行環境為：eclispe+jdk1.8+maven
搭建spring boot環境
首先建立maven project,在生成的pom文件中加入依賴，代碼如下：
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<parent> <groupid>org.springframework.boot</groupid> <artifactid>spring-boot-starter-parent</artifactid> <version>1.5.2.release</version> <relativepath/> <!-- lookup parent from repository --></parent><properties> <project.build.sourceencoding>utf-8</project.build.sourceencoding> <project.reporting.outputencoding>utf-8</project.reporting.outputencoding> <java.version>1.8</java.version></properties><dependencies> <dependency> <groupid>org.springframework.boot</groupid> <artifactid>spring-boot-starter-web</artifactid> </dependency> <dependency> <groupid>org.springframework.boot</groupid> <artifactid>spring-boot-starter-test</artifactid> </dependency> <dependency> <groupid>org.mybatis.spring.boot</groupid> <artifactid>mybatis-spring-boot-starter</artifactid> <version>1.3.0</version> </dependency> <dependency> <groupid>mysql</groupid> <artifactid>mysql-connector-java</artifactid> <scope>runtime</scope> </dependency> <!--分頁插件--> <dependency> <groupid>com.github.pagehelper</groupid> <artifactid>pagehelper-spring-boot-starter</artifactid> <version>1.2.1</version> </dependency> <!-- alibaba的druid數據庫連接池 --> <dependency> <groupid>com.alibaba</groupid> <artifactid>druid</artifactid> <version>1.0.29</version> </dependency></dependencies><build> <plugins> <plugin> <groupid>org.springframework.boot</groupid> <artifactid>spring-boot-maven-plugin</artifactid> </plugin> <!-- mybatis generator 自動生成代碼插件 --> <plugin> <groupid>org.mybatis.generator</groupid> <artifactid>mybatis-generator-maven-plugin</artifactid> <version>1.3.2</version> <configuration> <configurationfile>${basedir}/src/main/resources/generator/generatorconfig.xml</configurationfile> <overwrite>true</overwrite> <verbose>true</verbose> </configuration> </plugin> </plugins></build> |
配置好依賴后進行maven install,此時注意的坑：
坑一：啟動maven install報錯：
[error] failed to execute goal org.springframework.boot:spring-boot-maven-plugin:1.5.2.release:repackage (default) on project springboot-mybatis: execution default of goal org.springframework.boot:spring-boot-maven-plugin:1.5.2.release:repackage failed: unable to find main class -> [help 1]
[error]
[error] to see the full stack trace of the errors, re-run maven with the -e switch.
[error] re-run maven using the -x switch to enable full debug logging.
[error]
[error] for more information about the errors and possible solutions, please read the following articles:
[error] [help 1] http://cwiki.apache.org/confluence/display/maven/pluginexecutionexception
報錯原因是沒有啟動類
解決方法:編寫啟動類main.java正常運行！
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@springbootapplicationpublic class main { public static void main(string[] args) { springapplication.run(main.class, args); }} |
坑二：啟動maven install報錯：
[error] failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project springboot-mybatis: compilation failure
[error] no compiler is provided in this environment. perhaps you are running on a jre rather than a jdk?
[error] -> [help 1]
[error]
[error] to see the full stack trace of the errors, re-run maven with the -e switch.
[error] re-run maven using the -x switch to enable full debug logging.
[error]
[error] for more information about the errors and possible solutions, please read the following articles:
[error] [help 1] http://cwiki.apache.org/confluence/display/maven/mojofailureexception
報錯原因：項目的java環境與電腦環境不符合，例如我的新建項目運行環境為j2se-1.5,報錯是在我將其改為jre1.8之后
解決方案：
右鍵項目——build path——configure build path——libraries——雙擊jre system libraries如下圖所示：
選擇alternate jre 如2處的下拉框只有jre，點擊3處的install jres，依次經過add——standard vm——next——directory,選擇本機的jdk位置點擊finish
在install jres位置將默認勾選更改jdk,如下圖所示，并保存。
再次maven install項目正常。如下所示：
[info] build success
[info] ------------------------------------------------------------------------
[info] total time: 3.351 s
[info] finished at: 2018-09-05t21:20:48+08:00
[info] final memory: 23m/181m
[info] ------------------------------------------------------------------------
在src/main/resources新建文件：application.yml，內容如下所示：
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server: port: 8080spring: datasource: name: test url: jdbc:mysql://localhost:3306/test username: root password: 123456 driver-class-name: com.mysql.jdbc.driver## 該配置節點為獨立的節點mybatis: mapper-locations: classpath:mapper/*.xml#pagehelper分頁插件pagehelper: helperdialect: mysql reasonable: true supportmethodsarguments: true params: count=countsql |
至此springboot環境搭建完畢！
逆向工程應用
首先應該注意到在pom文件中有配置逆向工程xml文件的位置：src/main/resources/generator/generatorconfig.xml
因而在src/main/resources下新建generator文件夾，并建立generatorconfig.xml文件，代碼如下：
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<?xml version="1.0" encoding="utf-8"?><!doctype generatorconfiguration public "-//mybatis.org//dtd mybatis generator configuration 1.0//en" "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd"><generatorconfiguration> <!-- 數據庫驅動:選擇你的本地硬盤上面的數據庫驅動包--> <classpathentry location="e:\plugins\maven\repo\mysql\mysql-connector-java\5.1.41\mysql-connector-java-5.1.41.jar"/> <context id="db2tables" targetruntime="mybatis3"> <commentgenerator> <property name="suppressdate" value="true"/> <!-- 是否去除自動生成的注釋 true：是 ： false:否 --> <property name="suppressallcomments" value="true"/> </commentgenerator> <!--數據庫鏈接url，用戶名、密碼 --> <jdbcconnection driverclass="com.mysql.jdbc.driver" connectionurl="jdbc:mysql://localhost/test" userid="root" password="123456"> </jdbcconnection> <javatyperesolver> <property name="forcebigdecimals" value="false"/> </javatyperesolver> <!-- 生成pojo類的位置--> <javamodelgenerator targetpackage="com.luis.entity" targetproject="src/main/java"> <property name="enablesubpackages" value="true"/> <property name="trimstrings" value="true"/> </javamodelgenerator> <!-- 生成映射文件的包名和位置--> <sqlmapgenerator targetpackage="mapper" targetproject="src/main/resources"> <!-- enablesubpackages 是否讓schema作為包的后綴--> <property name="enablesubpackages" value="false"/> </sqlmapgenerator> <!-- 生成mapper接口的位置--> <javaclientgenerator type="xmlmapper" targetpackage="com.luis.mapper" targetproject="src/main/java"> <!-- enablesubpackages 是否讓schema作為包的后綴--> <property name="enablesubpackages" value="false"/> </javaclientgenerator> <!-- 指定數據庫表 --> <table schema="" tablename="user"></table> </context></generatorconfiguration> |
根據個人環境將配置文件中的配置進行更改，如數據庫密碼，包名，對應數據庫表
所用的數據庫表如下：
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drop table if exists `user`;create table `user` ( `id` bigint(20) not null, `name` varchar(255) not null, `age` int(4) not null, primary key (`id`)) engine=innodb default charset=utf8;insert into `user` values ('1', 'wanger', '22');insert into `user` values ('2', 'zhangsan', '18');insert into `user` values ('3', 'lisi', '23');insert into `user` values ('4', 'wangwu', '21'); |
配置完成后，右鍵項目，選擇run as——maven build——在下面兩處分別填入：
goals: mybatis-generator:generate -e
profiles: generatorconfig.xml
如下圖所示：
出現如下所示，代碼生成成功，刷新項目即可。
[info] generating example class for table user
[info] generating record class for table user
[info] generating mapper interface for table user
[info] generating sql map for table user
[info] saving file usermapper.xml
[info] saving file userexample.java
[info] saving file user.java
[info] saving file usermapper.java
[info] ------------------------------------------------------------------------
[info] build success
[info] ------------------------------------------------------------------------
需要注意的是：逆向工程生成的代碼不會覆蓋，因而不能重復多次生成。
此處也有個小坑，逆向工程的代碼生成后，啟動項目會報如下錯誤：
***************************
application failed to start
***************************description:
field usermapper in com.luis.service.impl.userserviceimpl required a bean of type 'com.luis.mapper.usermapper' that could not be found.
action:
consider defining a bean of type 'com.luis.mapper.usermapper' in your configuration.
解決方案：
1、給生成的mapper接口文件前加注解：@mapper 即可解決。但需要給每一個mapper文件前加，繁瑣，因而有第二種類
解決辦法
2、在啟動類前加@mapperscan({"com.luis.mapper"})，其中com.luis.mapper為mapper文件的所在位置。
參考自：http://412887952-qq-com.iteye.com/blog/2392672
分頁應用
逆向工程已經生成了entity類，及dao層的mapper接口與*mapper.xml文件，因而/只用編寫service層與web層。
首先在userservice中編寫接口，代碼如下：
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public interface userservice { user selectbyname(string name); list<user> findalluser(int pagenum, int pagesize);} |
在userserviceimpl文件進行實現，代碼如下所示：
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@servicepublic class userserviceimpl implements userservice { @autowired private usermapper usermapper; @override public user selectbyname(string name) { userexample example = new userexample(); criteria criteria = example.createcriteria(); criteria.andnameequalto(name); list<user> users = usermapper.selectbyexample(example); if (users != null && users.size() > 0) { return users.get(0); } return null; } /** * pagenum 開始頁數 * pagesize 每頁顯示的數據條數 */ @override public list<user> findalluser(int pagenum, int pagesize) { //將參數傳給方法實現分頁 pagehelper.startpage(pagenum, pagesize); userexample example = new userexample(); list<user> list = usermapper.selectbyexample(example); return list; }} |
最后在controller層對查詢結果進行接收，usercontroller代碼如下：
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@controller@restcontrollerpublic class usercontroller { @autowired private userservice userservice; @requestmapping("/test") public user queruserbyname() { user user = userservice.selectbyname("luis"); system.out.println(user.tostring()); return user; } @requestmapping("/list") public list<user> queruser() { list<user> list = userservice.findalluser(1, 2); //獲取分頁信息 pageinfo<user> pageinfo = new pageinfo<>(list); system.out.println("total:" + pageinfo.gettotal()); system.out.println("pages:" + pageinfo.getpages()); system.out.println("pagesize:" + pageinfo.getpagesize()); return list; }} |
測試
此前在項目編寫過程中已經對可能出現的錯誤進行了總結，最后，對項目的功能進行測試，通過加@restcontroller注解將數據傳輸到瀏覽器中。
測試mybatis與springboot，瀏覽器輸入http://localhost:8080/test，瀏覽器輸出：
{"id":1,"name":"wanger","age":22}
分頁測試，瀏覽器輸入http://localhost:8080/list，瀏覽器輸出：
[{"id":1,"name":"wanger","age":22},{"id":2,"name":"zhangsan","age":18}]
eclipse輸出：
total:4
pages:2
pagesize:2
項目搭建完畢，具體代碼參見github
總結
以上所述是小編給大家介紹的mybatis逆向工程與分頁在springboot中的應用，希望對大家有所幫助，希望對大家有所幫助，如果大家有任何疑問請給我留言，小編會及時回復大家的。在此也非常感謝大家對服務器之家網站的支持！
原文鏈接：https://www.cnblogs.com/liuyi6/archive/2018/09/06/9595856.html
